1. Field of the Invention
The present invention relates to a vision tester, and more particularly to a vision tester that is capable of measuring a dynamic visual acuity.
2. Description of the Prior Art
A static vision tester measures the ability to see things that are not moving, which is to say, static visual acuity. However, when a person is driving a car, it is necessary for the driver to be able to judge, quickly and accurately, obstacles, signals, signs, and so forth, and as such, emphasis is being placed on the measurement of a dynamic visual acuity. The dynamic visual acuity is the term used to designate the ability of an observer to discriminate an object when there is relative movement between the observer and the object.
The reduction of the dynamic visual acuity is accelerated and expanded by such factors as speed, fatigue and advancing age, and at high speed the dynamic visual acuity can be halved. Thus, imprecise judgement with respect to the danger involved means that driving at high speed becomes dangerous, so it is important to measure the dynamic visual acuity.
Up until now, however, there has not been any vision tester that can quantitatively measure the dynamic visual acuity, simply and accurately.
An object of the present invention is to provide a vision tester that has a simple arrangement and is able to accurately measure a dynamic visual acuity.